Automatic control



Dec. 16, 1947.

c. F. KTTERING Erm.

AUTOMATIC CONTROL Original Filed Aug. 3, 1942 2 Sheets-Sheet 1 I,-xacquul 2,432,667 AUTOMATIC CONTROL Charles F. Kettering and Albert W.Fischer, Detroit, Mich., assignors to General Motors Corporation,Detroit, Mich., a corporation of Dela- Ware Original application August3, 1342, Serial No.

453,357. Divided and this application November 2, 1944, Serial No.561,560

7 claims. (o1. 25o-471.5)

This invention relates to automatic control means and more specificallyto means to automatic'ally maintain a mobile body on a predetermined 'orset course. In the operation of mobile craft, such as ships orairplanes, it is very desirable to have thereon means which may be setto hold a course and to have this means automatically maintain suchcourse for a period of time. By some means, such as the above, theoperators or pilots thereof are relieved of much tedious duty or suchautomatically controlled craft may be preset and dispatched with nopersonnel on board and will reach its objective afs in the caseof atorpedo. This application is a division of our Patent 2,377,698, issuedJune 5, 1945. d

n It is therefore an object of our invention to provide means that willautomatically maintain a self-propelled body on a predetermined setcourse.

Itis a further object of our invention to provide automatic steeringmeans which requires no attention after it has been set. y

It is a still further object of our invention to provide automaticsteering means that is simple and rugged.

With these and other objects in view which will become apparent as thespecification proceeds, our invention will be best understood byreference to the following specification and claims and the.illustrations in the accompanying drawings, in which:

Figure 1 is a schematic view showing the essential parts of our controlsystem;

Figure 2 is an enlarged sectional View taken on line 2-2 of Figure 1;

Figure 3 is a circuit diagram of the electrical connections of ourinvention; Y

Figure 4 is an enlarged vertical section through the compass unit;

n Figure 5 is a sectional view taken substantially on line 5-5 of Figure6;

Figure 6 is a horizontal section taken on line 6 6 of Figure ,4; and,

, Figure 7 is a top detailed view of the master compass magnetsand theirmounting.

Referring now more specifically to the drawings, there is shown inFigure 1 steering mechanism indicated generally at 2 for` operating therudder of a self-propelled craft such as a boat: or plane. A drivingmotor 4 is utilized to physically turn the steering mechanism and thusthe rudder to predetermined points and this motor is a small reversibleone which is' supplied by power from a suitable power source 6 which inFigure 1 also houses necessary amplifying apparatusl The means formaintaining the steering mechanism and the rudder in the necessarypositions is primarily a compass unit indicated generally at whichthrough means tobe described controls the motor 4 to set the rudder.

'I'he particular steering mechanism in this instance is disclosed forpurposes of illustration only as being a steeringwheel of a boat whichwheel is mounted upon a shaft I0 connected to the steering mechanism orrudder by suitable means not shown. This shaft I0 carries a sprocketwheel I2 loosely mounted`on the shaft inside'of the head I4 of thesteering wheel per se I6. A collar I8 fitting inside the steering wheeland surrounding the hub of the sprocket I2 is mounted on the steeringwheel through spaced peripheral pins 20 connected to a disc 22 on theouter face of the steeringwheel. This disc 22 has a central operiing 24therein which is internally threaded and through which a thumb screw 26is insertedv to press against the hub of the steering wheel to cause theassembly to beY pulled outwardly.

To the face of the hub of the sprocket I2 is positively secured byrivets a ring 28 and to the inner face of the steering wheel and inalignment with the ring 2B is rigidly secured a collar 30 of frictionmaterial such' as brake lining. Thus when the screw 26 is manuallyforced against the hub of the wheel, the collar I8 is pulled outwardlyand locks the ring 28 against the friction material 3U so that thesprocket wheel I2 will rotate with the steering wheel at all times. Thisis necessary to allow at certain intervals relative motion between thewheel and sprocket so that adjustments may be m'ade.

A driving chain 32 indicated by the dotted lines in` Figure 1 is fedover the sprocket I2 and also over a second sprocket 34 on the motorshaft, whereby as the motor turns, the steering wheel and rudder willalso be turned or adjusted. A plurality of flexible drive means are alsodriven by the motor 4, one of which comprises a Bowden Wire connection3.8 between the motor and an indicating member 40. Thus as the motor 4rotates, such rotation will actuate the indicating apparatus 4|! toinform the operator as to the course' upon which the control is set andwhich will be followed. At the same time a follow-up mechanism for thecompass is operated through xible drive 36.

The compass mechanism per se which has been indicated generally at 8consists of a substantially cylindrical housing 42 which is covered by acap $4; A supporting moss panel 46 is provided in the 3 base of thecylindrical member and is permanently fixed therein. This base has acentral aperture therein in which is mounted a bushing 48 through whicha short stub shaft 50 projects. Mounted upon the inner or upward end ofthe shaft 50 is a disc member 52 of only slightly smaller diameter thanthe casing. This disc carries about its periphery a, drum 54 formed ofinsulating material and in the exterior surface of this drum are carriedspaced conductive rings 56 providing sliding contactors for a series ofspring biased terminals 58 which cooperate therewith, said terminals 58being connected to individual wires provided in a connecting cable 60which conducts them back to the power supply and amplifier. Thus as thestub shaft 50 turns, all of the mechanism carried thereby will also haveits angular position altered. The terminals 58 are carried in the sideof a casing by an insulating block 6| and have portions bearing againstthe surface of these circular conductive inserts in the insulating drum54. Thus any power from other parts of the apparatus is conducted tomechanism carried by the rotating means.

through the terminals and conductive rings.

On the lower end of the stub shaft 50 there is secured a gear 62 whichis connected to the rotating shaft 50 and engages the gear driven by theBowden wire means 36 and is therefore driven by the motor 4 in itsrotation. Secured to the upper face of the disc 52 is a flanged bellmember 64 which has stretched across its inner portion a corrugateddiaphragm member 66 to seal the same from the atmosphere. The centralportion of this bell at the top is provided with an opening throughwhich a hollow bushing 68 passes, said hollow bushing securing a largehollow spherical body 10 thereto. In the hollow section of the upperportion of the bushing 68 is inserted one end of a tapered rod 12. Onthis rod at substantially the midpoint thereof is fastened a disc 14 anda concentric coil spring16 is mounted around the rod bearing against thedisc 14 and a shoulder on the outer surface of the bushing 68. Thistends to eject the rod from the bushing or force it upwardly as shown inFigure 4 to provide a spring mounting for means to be described.

'I'he spherical member 10 and the interconnected enclosure formed by thebell member 64 and diaphragm 66 which forms an auxiliary expensionchamber are adapted to be filled with a fluid 18 and in this fluid bathand pivotally mounted upon the upper end of the tapered rod 12 is ahollow circular member 80. The circular member 80 has a concave conicalopening in the. bottom surface into the extremity of which the tip ofthe tapered rod 12 projects and upon which the member 80 is balanced onthis pivot point. The member 80 is sealed and therefore maintains airthere- 'in and carries on the inner surface of the conical portion apair of spaced parallel magnets 82 and 84 which are clamped thereto bysmall collars 86. These two magnets are. built un of Alnico portions 88and 90 separated by a soft iron spaced 92 to form north and south poles.

The float or member 80 is submerged in the liquid 18 to buoy unapproximately 90% of the weight of the magnet assembly and the taper onthe conical reentrant opening in the. bottom face of the assembly isdesigned so that the float may pivot 30 in any direction from vertical.Vanes 94 are provided upon the outer surface of the member 80 to furnishdamping for movements of the magnet housing. The two magnets 82 and 84are parallel and when placed in the earths magnetic neld tend to alignthemselves. and, the. @Oat CROSS REFERENCE 4 therewith to indicatedirection. Spaced above each of the master magnets 82 and 84 and alignedtherewith are two auxiliary magnets 96 and 88 which are supported fromthe inner surface of the float and are directly above the other twomagnets.

The upper surface of the substantially spherical member 10 is depressedto form a hollow portion and in the center of this hollow portion thereis pivotally mounted a small vertical rod |00 which carries thereon amirror |02. A transverse bar |26 is centrally affixed to the verticalrod |00 and carries at its outer extremities two small slave magnets |28and |30 whose position is controlled by the larger magnets and which dothe actual turning of the mirror for control purposes. The lower end ofthis rod is pivoted at |04 which is the center of the depressed portionand a bracket |66 connected to the upper surface of the member 10carries the upper pivot |08 which is adjustable to allow the shaft to beclamped firmly but to pivot freely in its two aligned pivots.

A small platform ||0 is also carried by the upper surface of the member10 and an uptumed flange ||2 carries a light ||4, the rays from whichproject through a panel ||6 having an opening ||8 therein. These lightrays fall upon a pair 0f lenses |20 which project them onto a reflectingsurface |22 which surface is concave and converges the rays upon theadjustable mirror |02 whose position is determined by the compass means.The rays are then caused to fall upon a photoelectric cell |24 orsimilar light sensitive device, the output of which is fed through theterminals to the amplifier. Thus the position of the mirror |02, asdetermined by the magnets or compass needles, determines the amount oflight falling on the photoelectric cell and the output thereof which isamplified determines the operation of the control motor.

Referring now more specifically to Figure 3, there is shown therein thephotoelectric cell |24 which is connected to an amplifier |32 bysuitable lines |34 and |36. The light source or bulb ||4 is connectedacross the power source by lines |38 and |40. A battery |42 provides theenergy for the system and is connected to the amplifier by lines |44 and|46. The output of the amplifier is connected to two relays |48 and |50in series by lines |52, |54 and |56. Relay |48 operates an armature |51and relay 50 operates an armature |58. When the relays are energized,the armatures are in their lower position, and when deenergzed, in theirupper position. Both armatures are spring biased to their inoperative ordeenergized position, but the spring bias on armature on |51 is alwaysless than that on armature |58 and therefore with the same currentflowing through both relays, armature |51 will be attracted previous to|58.

Armature 51 oscillates between two contacts |60 and |62, the first ofwhich is connected by line |64 to one side of the battery |42 and thesecond of which is connected by line |66 to contact |68 of the lowerarmature |58 and also by line |10 to line |46. The lower contact |12 ofthe lower armature |58 is connected to line |64 and thus to the battery.The two armatures |51 and |58 are directly connected electrically to thedriving motor 4 of the device.

In operation thereof the compass and indicator are set for a particularcourse and are adjusted with respect to the steering wheel by unlockingthe friction arrangement described and shown in Figure 2 and when theyhave been set rimarra on the course the thumb screw 2 6 is locked. Thedevice or craft is then started upon its course and the amounts ofdeviation from said course vary the position of the magnet compassmembers 82 and 84 and their float with respect to the substantiallyspherical housing 10. This causes the slave magnets |28 and |30 to movethe mirror about its pivot and therefore vary the amount of light thrownon the photoelectric cell.

The outputV of said photoelectric cell is fed through the amplifier andapplied 'to the two -re lays |48 and |50 in series.- If the crafthas notdeviated sufficiently from its course in one direction to warrantcorrection, the amount of c urrent owing in the relay-circuits will beinsuicient to cause them to be attracted and they will therefore havetheir armatures in their upper position and the motor 4 continues to beener gized lto turn in one direction through thefollowing circuit:battery |42, line |44, line |64, contact |60, armature |56, motor 4,armature |58, contact |68, line |10, line |46, back to the battery |42.This will cause the rudder to turn in one direction.

However, when a sufficient correction or movement of the rudder in onedirection has been obtained, the light on the photoelectric cell willbecome more and more intense and the current flowing in the relaycircuits will increase until such time as relay |48 has a sufficientcurrent to attract its armature |51. This will break the motor circuit,and since at this instant armature |53 is still up, no current will flowthrough the motor. The rudder will then remain in the position set whichwill probably be to cause the boat to turn further off course and whenthe light intensity increases still further, the relay |50 will besufficiently energized to attract its armature |58 and both armatures|51 and |58 will now be in their lower or energized position and themotor 4 will be caused to rotate in the opposite direction to thatpreviously described and the rudder will be moved back to cause acorrection in the opposite direction.

It will therefore be obvious that the control mechanism will cause themotor to move the rudder first slightly in one direction and thenslightly in the opposite direction, but this is not strictly a huntingsystem because there is a. period when one relay attracts its armatureand the other does not when the motor has a deenergized or offcondition. As before stated, when the motor 4 operates it drives theindicator 40 through a ilexible cable drive, and simultaneously throughthe flexible cable drive 35 causes a worm |14 to turn i the gear 62 as afollow-up mechanism to adjust the position of the main portion of thecompass means to decrease the variation or amount of correction appliedthereby.

We claim:

1. In control means, a hollow body, magnetic means sensitive to theearth's magnetic field pivotally mounted within saidvhollow body, asource of light and a light sensitive cell mounted in spaced relation onsaid hollow body, light interrupting means pivotally mounted exteriorlyof said hollow body to control the ilow of light from the source to thecell and slave magnet means secured to said last named pivotal means toduplicate the movement of the first named magnetic means and control theenergization of said cell in relation to the position of the magneticmeans.

2. In control means, a hollow body, magnetic means sensitive to theearths magnetic eld pivotally mounted within said hollow body, a sourceofflightand a.- lighti sensitivecell mounted gv in spaced relation ,onsaid hollow body, a series; Qi reecting means mounted exteriorly of saidhollow body between the source and the cell to Vdirect the light raysupon the. cell, pivotal mounting means for a part of the reecting meansto vary the intensity of light falling on said cell and slavemagnet-means rigidly connected to the pivoted means influenced by therst named magnetic, means to control the position of said pivoted meansand the proportionate amount of. light falling on said cell as dictatedby the positionof the first named magnetic means.

3'. In control apparatus, a housing, a hollow body adjustably mountedwithin the housing, a iioat pivotally mounted within the hollow body,liquid iilling the space within the hollow body and buoying up thefloat, magnetic means carried within the iioat, second magnetic meanspivotally carried by the hollow body in juxtaposition to the iioatwhereby the two magnetic means will align themselves, a source of lightcarried on the hollow body, light sensitive means also carried on thehollow body and means on the pivotal mounting exteriorly of the hollowbody for the second magnetic means to vary the amount of light from thesource that falls on the light sensitive means whereby the position ofthe first magnetic means controls the amount of light falling on thelight sensitive means and thus the output of the means.

4. In control apparatus, a housing, a hollow body adjustably mountedwithin said housing, uid filling said hollow body, a oat pivotallymounted within said hollow body and buoyed up by said fluid, magneticmeans carried by said float, a second magnetic means pivotally carriedexteriorly of said hollow body in juxtaposition to said float wherebythe magnetic means will align themselves, a source of light carried onsaid hollow body, a light sensitive means carried on said hollow body,means operated by movement of the second magnetic means to vary theamount of light on the light sensitive means and slidable electricalcontactor means to conduct current to and from the radjustable hollowbody.

5. In control apparatus, a horizontally disposed magnet rigidly mountedon a vertical spindle having freedom of rotary motion in a horizontalplane, a source of light, a light sensitive means, a light reflectingmeans mounted in a vertical plane substantially on the axis of rotationof and carried by said magnet, said light source and said lightsensitive means so positioned that rays from the light source arereected by the reflecting means to vary the light falling on the lightsensitive means and thus control the electrical output of said lightsensitive means.

6. In control apparatus, a hollow body, a magnetic means sensitive tothe earths magnetic eld pivotally mounted in said hollow body, saidmagnetic means mounted by suspension means above its center of gravitywith unlimited movement in the horizontal plane and limited movement inthe vertical plane, a second magnetic means pivotally carried by saidhollow body in juxtaposition with said first magnetic means whereby said.magnetic means will align themselves, a source of light carried on saidhollow body, a light sensitive means carried on said hollow body, meansoperated by movement of the second magnetic means to vary the amount oflight on the light sensitive means and thereby control the electricaloutput of said light sensitive means,

7 7. In an electrical control device, a light sensitive means, and alight source mounted in ilxed relation to each other, a magnetic meanssensitive to the earths magnetic field mounted free to move in aplurality of planes relative to said first mentioned means, a secondmagnetic means with freedom of movement in only one plane controlled bythe magnetic eld of said rst magnetic means, a light reflecting surfacerigidly carried by said second magnetic means so positioned andassociated with said light source and light sensitive means to controlthe amount of light falling on said light sensitive means from saidlight source.

CHARLES F. KEI'IERING. ALBERT W. FISCHER.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,819,439 Peterson Aug. 18, 19312,289,242 Chance et al July 7, 1942 1,779,991 Sperry Oct. 28, 19302,112,490 Hill Mar. 29, 1938 1,818,103 Sperry Aug. 11, 1931 2,377,698Kettering June 5, 1945 2,112,504 Mireld Mar. 29, 1938 1,885,098 Hill'Oct. 25, 1932

